Water-Energy Nexus: Can Nanotechnology Provide Solutions?
Shaurya PrakashDepartment of Mechanical & Aerospace Engineering
The Ohio State University
Water for the Americas
February 11, 2014
Water
Materials Food, agriculture
Energy
Societal Operations
Functional modern society
Economic development
Environment sustainability
Health and Wellness
Security
Water and Energy are Interdependent
• Thermoelectric cooling
• Hydropower
• Energy minerals extraction/ mining
• Fuel Production (fossil fuels, H2, biofuels, shale)
• Emission control
• Pumping
• Conveyance and Transport
• Treatment
• Use conditioning
• Surface and Ground water
Information Courtesy: Michael Hightower, Sandia National Labs, 2010
Energy and power production require water
Water production, processing, distribution, &
end-use require energy
United States Water Usage
Public and Self-supplied Potable Water
40,738.5(12%)
Industrial-Mining27,159.0-
(8%)
Irrigation-Livestock139,189.7 MGD
(41%)
• Total water withdrawn per year 123.9 trillion gallons, which is ~ yearly outflow of Mississippi river
• Direct energy demands (TE power generation) currently accounts for ~ 39% of all water withdrawal
Water Withdrawn in the US for All Uses
Thermoelectric Power
132,400.0(39%)
Costs directly
related to withdrawals:
Source matters
“Consumptive Water Use for U.S. Power Production,P. Torcellini, et.al., National Renewable Energy Laboratory, 2003.
Water and Energy: Two Sides, One Coin
• As just discussed, energy accounts for the largest water withdrawal including mining, refining, and generation
• Coal use for generation increases water loss by 33% over natural gas and nuclear. Coal to H2 doubles loss rate consumptive use!
• New sources of energy (biomass, syngas, hydrogen) will more than double current use per gallon or kWhr (4-6 gal. H2O/gal ethanol)
• Water withdrawals expected to be TWO orders magnitude larger with increased ‘new’ energy
Information Courtesy: Mark Shannon, U. Illinois
Impact on Energy
Without sufficient water: Challenging to increase energy use to meet the
needs of a growing population Difficult to transition to a hydrogen economy Our ability to use biomass and clean coal derived
fuels will be impacted We’re the Saudi Arabia of Shale Oil and Gas, but we
can’t utilize it without proper water use and disposal Increased demands for electricity for using plug-in
hybrid vehicles will be impacted as electric power generation is limited by water use
Can it be Worse? Population Growth (>1% per year ) and Population Shifts to Urban
Areas: Changes and increases demand in water, food, and energy• Local problems growing
• Logistics for distribution, management, maintenance will only get harder
Over-pumping of Ground Water Aquifers: Unsustainable Water, Energy, and Food: The complete nexus Contamination of Source Waters: Cross-contamination of surface
and aquifers is growing, reducing dilution solutions – more treatment is needed new technology is imperative• Finite (and increasing) energy costs
Current centralized water systems are capital, energy, and chemically intensive, and new systems are neither sustainable or affordable for growing populations
Snowpack Storage and Glacial Melting: Major river systems with shortages during dry months (Brahmaputra, Ganges, Yellow, Mekong Rivers, Blue Nile, Mt. Kilimanjaro, Andes, Rio Grande, Lake Mead, etc.)
Can Nanotechnology Help?
Nanotechnology provides unique opportunities• Provides physical basis for evaluating fundamentals
of how molecules interact
• Can build transformative advances by harnessing the ability to manipulate the basic building blocks of materials and systems
• System components and functional units will be at same length scales as physical phenomena that govern water processes
Basis for new technology solutions
Nanotechnology Can Help With…
Use chemicals only as needed: No more homogeneous chemical mixer systems to heterogeneous chemistry systems: catalysts, separators, absorbers, membranes (passive and active), biochemical, nanotechnology,…
Wastewater is Resource-water: Recovery of chemicals from wastewater – nutrients, ammonia, methane,…
Less exogenous energy: Increased renewables solar, wind, energy from waste (including wastewater),…
Sustainability from nature: Bio-inspired processes for contaminant detection, separation of contaminants and salts, bio-remediation of solids in wastewater, …
Desalination Example – Opportunity for Innovation
Current water desalination methods can be energy intensive
Process MSF MED/TVC RO ED*
Heat Consumption (kJ/l) 290 145-390 -- --Electricity Consumption (kJ/l) 10.8-18 5.4-9 9-25.2 4.32-9
Total Energy Consumption (kJ/l) 300.8-308.8 150.9-399 9-25.2 4.32-9
Typical Production Capacity (m3/day) ~ 76,000 ~ 36,000 ~ 20,000 ~ 19,000
Conversion to Freshwater 10-25% 23-33% 20-50% 80-90%Pretreatment required little little demanding moderate
* For brackish water
We are far from the natural law limits for separating contaminants from water: Currently at 4-100X times higher for nearly all
methods Lots of room to improve!
Nanotechnology Solutions for New Desalination Systems
Biological systems are close to thethese limits, and operate at the nanoscale
New water purification technologies using point-of-source supply, point-of-discharge, and point-of-use systems: The new (oldest) paradigm in infrastructure
New technologies can greatly improve how clean water is supplied and sanitation discharged – Can change everything!
Kim, S. J. et al. Nature Nanotechnology 2010
Chip-scale system at MIT to deliver de-salted water from seawater at a fraction of the energy cost
First generation lab device at OSU inspired by biology for desalination at thermodynamic limits
Prakash, S. et al., in Bionanotechnology II, CRC Press, 2011, Reisner, D. (Ed.)Prakash et al., Patent Pending (2013)
Paradigm Shift: Wastewater is Resource-Water – Extract Energy
U.S. municipal wastewater contains 7.2x109 kg of “dry solids” annually
• ~ 25 MJ/kg (7 kW.hr/kg) of energy content
• Total energy available ~2x1017 J (51 billion kW.hr).
Currently, most municipalities do not generate energy from bio-solids:
• 49% treated & applied to land, 45% incinerated or landfilled, 6% to other
U.S. 2008/2009 electrically generated: 14x1018 J
Energy content in wastewater is ~ 2% of US electrical demand(Nearly equivalent to energy from major renewables combined,
solar, wind, etc.)
Integrated Anaerobic Digester for Bio-Ammonia Harvesting
Harvest bio-gas (methane) and ammonia
Integrate with anaerobic digester with novel thermophilic microbes resistant to high ammonia concentration
Integrate with fuel harvesters
> 20% total enhancement in energy with hydrogen from ammonia in addition to methane possible!
Babson, Prakash et al. Biomass & Bioenergy (2013)
High Efficiency Microbial Fuel Cells
Energy extraction from waste (and wastewater)
Current technology limited by poor system efficiency
Bio-inspired structural designs to exploit fundamental features
• Sea-corals• Cow rumen
New materials for high efficiency operation
Gerber, Prakash et al. (2014)
Summary and Conclusions
Basic science
Conservation
Public-private partnerships
Economic opportunities in emerging markets
Technology innovation
Systems development
Implementation to central infrastructure
Creation/implementation to point-of-use infrastructure
Water-energy sustainability
Water and Energy is a coupled problem and must be addressed by bringing in ‘stakeholders’ at all levels (local to federal government, private enterprises, utilities, consumers, technology development, and market transition).
Acknowledgements
Prof. Mark Shannon (U. Illinois) Prof. A.T. Conlisk (Ohio State) Prof. D.E. Fennell (Rutgers) Matt Gerber, Marie Pinti, Clare Cui, David Babson Financial support: NSF, DARPA, NJWRRI
Thank you!
Questions?
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